THE AMMONITE. 203 



group ; a sting which leaves after it a white pimple, like 

 that caused by a nettle. 



A remarkable interest is attached to the nautilus from 

 the very remote periods of time to which it can be traced ; 

 fossils being found in the most ancient rocks in which shell 

 animals have been discovered, in various parts of the world, 

 living ages before the Flood in temperate and tropical seas. 

 In the London clay, which forms such a large extent of the 

 substratum of the great metropolis, lie buried vast numbers 

 of the pearly shells of the nautilus, which, evidently at a 

 great distance of time, found in that country a congenial 

 climate and home. The largest British specimens of the fos- 

 sil nautilus occur in the carboniferous limestone, and speci- 

 mens of these are preserved in the British Museum more 

 than a yard in length, and thick in proportion. 



In the museum of the Royal College of Surgeons, in 

 London, is a specimen of the entire animal, soft parts and 

 shell, of the pearly nautilus : a portion of the shell has been 

 removed to show some of the chambers, and the membranous 

 tube or syphon which traverses them. There is also a 

 specimen of the paper nautilus suspended as when floating, 

 with the expanded membranous arms in their natural posi- 

 tion spread over the shell which they form and repair. 



Resembling somewhat in appearance the nautilus, the 

 shell being chambered and spiral, but differing otherwise in 

 some respects, was the primitive navigator of the ancient 

 seas, the ammonite, of which the shells now only remain, the 

 most beautiful of all our fossils, and found in almost every 

 country in the world, upwards of two hundred species hav- 

 ing been described. The name is derived from a fancied 

 resemblance of its shell to the ram's horn ornaments on 

 sculptured heads of Jupiter Ammon. They are of very 

 different sizes, varying to even three or four feet in diameter. 

 The larger ones were formerly taken for petrified snakes, 

 and were found in great numbers at Whitby in Yorkshire. 



